Over the years, practitioners experienced in the use of culture media have learned that growth rates can be enhanced and the chance of disease can be reduced by modifying the culture medium. This modification can be achieved through the addition of a gas or gasses to the medium. For example, fish yield and disease reduction in a fish hatchery or farm can be significantly enhanced by adding a gas, such as oxygen, to the culture medium, such as water.
In the past, a water culture medium has been modified through aeration, which is accomplished by spraying the medium into the air or by agitating it by means of paddles or the like. This method, however, results in the addition of nitrogen to the medium as the air is dissolved into the medium, a problem of significance to the fish culture industry. As fish consume the oxygen admitted by aeration, the nitrogen proportion in the water increases and can reach levels that are detrimental to life.
The prior art also teaches the introduction of pure oxygen into the culture medium by means such as bubbling, water towers and the like. These methods, however, have serious cost and effectiveness limitations. Concentrated oxygen is expensive, and the equipment required to dispense the oxygen often represents a substantial investment. Additionally, one of the most limiting aspects of gas addition to fluids is the inherent tendency of any such added gas to disassociate itself from the fluid carrier over time during agitation, pumping, or movement. Prior to the present invention, there have been essentially no practical, low-cost devices specifically designed for the efficient addition of gasses (including oxygen) to a fluid culture medium such as water.